Power driven rotary file



1957 B. A. HARRISON ETI'AL 2,815,686

POWER DRIVEN ROTARY FILE Filed May 4, 1956 INVENTORS BEA/y fl. HARE/SON g2 n lLL/flM J. AGENT gLMH-d w ATTORNEY v United States PatentO POWER DRIVEN ROTARY FILE Benjamin A. Harrison and William S. Agent, Sallisaw, Okla.

Application May 4, 1956, Serial No. 582,703

6 Claims. (Cl. 76-37) This invention relates to power-driven rotary files and, particularly, to a rotary file especially, although not exclusively, useful for sharpening chain saws.

The primary object of the invention is to provide a power driven rotary file capable of being manually held and manipulated so as to perform its work with great accuracy and force. A further object is to provide a rotary file having a power input coupling for connection with a flexible shaft drive.

In manipulating a hand file, the workman oftentimes grasps not only the handle at one end of the file with one hand, but he also places his other hand against the top of the free end of the file. In this manner both ends of the file are guided, the file is maintained at a fixed angle to the work, and great accuracy may be achieved. In flexible shaft driven rotary files heretofore devised, wherein the file extends freely beyond a combined handle and rotary shaft coupling, this sort of action is not possible because the free end of the file cannot be supported and, furthermore, whip in the free unsupported end of the file militates against accuracy, efficiency, and fineness of work. The object now is to provide a rotary file wherein both ends of the file are rotatably supported in a rigid combination handled and supporting frame so that the same accuracy attainable with a hand file may be achieved, and whereby tendency of the file to whip or vibrate against the work may be overcome.

A further object of the invention is to provide a rotary file assembly wherein both ends of the file are rotatably supported in a rigid handle-frame, but with provision for utilizing files of various lengths. Yet another object is the provision of a firm coupling with a flexible shaft drive, arranged so that the files can be mounted or unmounted without disturbing the shaft coupling and so that the shaft may be coupled or uncoupled without disturbing the file mount.

Also among the objects of the invention are the provision of a power driven rotary file whose main parts are standard, readily available elements, and whose adaptation for use in the proposed assembly is well within the capabilities of a small machine shop or factory; and the provision of an inexpensive, yet extremely durable tool capable of hard rough work under adverse conditions. These and other objects will be apparent from the following specification and drawing, in which:

Fig. 1 is a side elevation of the power driven rotary file;

Fig. 2 is a side elevation of one of the bushing sleeves;

Fig. 3 is a side elevation of one of the chucks; and,

Fig. 4 is an enlarged cross section showing the details of the combined chuck and shaft coupler assembly.

Referring now to the drawing, in which like reference numerals denote similar elements, the power file 2 comprises a rigid wide U-frame 4 having a handle 6 surrounded by a rubber grip 8. Handle 6 is preferably formed of a length of pipe, to the ends of which are threaded hollow angle couplings 10. The ends of the in T-coupling 12 2 angle couplings are threadedly connected to T-couplings 12, 12 whose heads are coaxial and parallel with ham dle 6.

Press fitting within each of the heads of T-couplings 12, 12 are bushing sleeves 14, these being bored at 16 to provide passages for oil. The hollow interiors of angle couplings 10 constitute oil reservoirsand are filled by removing threaded'screw plugs 18, it being apparent that an ample supply of lubricating oil may be main: tained in the hollow frame of the assembly.

Referring now to the right hand end of Fig. 2 and to Figs. 2 and 3, bushing sleeve 14 rotatably supports, a chuck 20 comprised of a cylinder 22 which is hollow, as indicated at 24, for most of its length. To one'end of cylinder 22 is rigidly afiixed a collar 26 through a radial bore of which is threadedly engaged a set screw 28. On other end of cylinder 22 is secured a thrust masher 30 by means of a screw 32 threadedly engaging in a suitably threaded hole in the closed end of cylinder 22. From Figs. 1 and 3 it will be apparent that chuck 20, while freely rotating in bushing 14, may also slide lengthwisebetween the limits defined by collar 26 and stop washer 30. Rotatably supported by bushing 14 within T-coupling 12 is a combined chuck and shaft coupler denoted generally at 34, comprising an internally threaded sleeve 36 which extends from end-to-end and rotating fits within bushing 14. A chuck 38 is formed of an externally threaded sleeve 40 threadedly engaging within the adjacent end of internally threaded sleeve 38, the sleeve 38 having rigidly aflixed on its exterior end a collar 42 with a set screw 44 therein and nut exterior surfaces thereon.

Threadedly engaged within the other end of internally threaded sleeve 36 is an externally threaded coupler sleeve 46, the latter also having internal threads 48 and a nut-surfaced collar 50 affixed on its ends. It will be apparent to those skilled in the art that the threads are arranged so that collars 42 and 50 may be engaged by wrenches for screwing the sleeves 40 and 46 into internally threaded sleeve 36. The internal threads 48 are for engaging the externally threaded end of a flexible drive shaft (not shown) running in flexible sheath 52.

In operation, set screws 28 and 44 are loosened so that the ends of a rotary file 54 may be inserted in chucks 20 and 34 and, because of the telescoping arrangement of coupler 20 within T-fitting 12, files of various lengths may be accommodated. When power is applied to the flexible shaft coupling, file 54 is rapidly rotated, the bearing surfaces of bushings 14 and the members rotating therein being amply supplied by lubricant via holes 16. Lubricant leaking from the bearings is slung off from the rotating cylinder 22 and sleeve 36, and shielded from the work or file 54 by collars 26 and 42.

Sharpening a chain saw represents a typical valuable usage of the file. With the saw chain suitably clamped in a jig, the power input end of the flexible drive shaft .may be connected to the saw drive shaft so as to rotate ing bearing supports, a bushing sleeve 'aflixed lip each of said heads, a hollow cylinder rotatably mounted in each of said bushings, one of said cylinders being longer than the bushing in which it is mounted whereby the same -may move axially in its bushing, thrust flanges at the ends of the last-named cylinder for retaining the same in said bearings, means on said hollow cylinder for engaging the same respectively with the ends of a rotary file, and detachable coupling means for connecting one of said cylinders to a drive shaft.

2. The combination claimed "in claim 1, said cross member being detachably connected at its ends to said tubular sides, and hand grip surrounding said cross memher.

3. The combination claimed in claim 1, said bushings each having a radial passage 'therethrough respectively communicating with the interior of the adjacent'hollow T-coupling, and lubricant filling means in said frame for injecting lubricant to the hollow interiors of said sides, whereby the same constitute lubricant reservoirs for said bushings and cylinders.

4. A powerdriven rotary file comprising a rigid open frame having a pair of generally parallel sides connected by a cross-member, said cross-member constituting a handle, coaxial bushings respectively afilxed on corresponding free ends of said sides, a chuck rotatably mounted in one said bushings for engaging one end of a rotary file, an internally threaded sleeve rotatably mounted in the other bushing, a second chuck for engaging the other end of said file, said second chuck having an externally threaded shank threadedly engaged in one end portion of said internally threaded sleeve, the other end portion of said internally threaded sleeve constituting a coupling element for threaded engagement with a rotary drive shaft, the other end of said sleeve terminating adjacent an end of said bushing, and a nut-surfaced stop collar afiixed on the other end of said sleeve for limiting axial movement thereof in one direction in said bushing.

5. The combination claimed in claim 4, said second chuck including a nut-surfaced stop collar thereon for limiting axial movement of said second chuck and sleeve in the other direction in said bushing.

6. A power driven rotary file, comprising a rigid open frame having a spaced pair of generally parallel sides connected by a cross member, first and second coaxial hollow cylindrical bearings disposed at corresponding free ends of said sides, first and second chucks rotatably mounted respectively in said first and second bearings, said chucks comprising hollow cylindrical members receiving the respective ends of a rotary file, flanges on said first chuck engaging the ends of said first bearing and restraining the first chuck against axial movement in the'first bearing, said second chuck being substantially longer than the second bearing, 'flanges .on the ends of said second chuck providing for limited axial movement of the second chuck in the second bearing, and internal screw coupling means on said first chuck for connecting the same to a rotary drive shaft.

References Cited in'the file of this patent UNITED STATES PATENTS 2,687,561 Anderson Aug. 31, 1954 

